Sharpening Grit Guide: From 200 to 6000 – Choosing the Right Stone or Abrasive for Sharpening
💎 Introduction: Gradual Sharpening, the Secret to Successful Sharpening
You now understand the vocabulary (Article 1) and the importance of a constant angle (Article 2). The next step, and perhaps the most practical, is to understand how the abrasive surface you are using works with the material. This is the role of the sharpening grains .
Whether you use a waterstone, an oilstone, or a rolling sharpener equipped with diamond discs, the quality of the work depends on the grit size. The secret to professional sharpening lies in methodical progression : first, remove the damaged material quickly with a coarse grit, then gradually refine the micro-scratches left by the previous grit to achieve a polished, sharp finish.
Let's discover together the grain scale and the correct sequence to follow.
1. What is a Sharpening Grain?
The concept of grain (or grit in English) corresponds to the size and density of the abrasive particles present on the surface of the tool (stone, grinding wheel, diamond disc).
1.1. Measurement Systems
Several standards exist, but the two main ones encountered are:
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JIS (Japanese Industrial Standards): The most common standard for water stones. The higher the JIS number, the finer the grit (less abrasive).
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FEPA (Federation of European Producers of Abrasives) / ANSI (American National Standards Institute): Used for other types of abrasives (grinding wheels, papers, diamond abrasives). The numbers may differ slightly for the same grit.
To simplify: We will use here the most common grit numbers (based on the JIS standard for examples) which represent a universal fineness in the world of sharpening.
1.2. From Brick to Mirror: The Role of Grain
The grain dictates the cutting speed and the finish:
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Coarse Grit (Low Grit): Remove a lot of material quickly (high abrasion rate). They leave deep scratches and are used to repair significant damage or change the angle.
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Fine Grits (High numbers): Remove very little material, but polish the surface and refine micro-scratches. They are used for finishing and achieving a razor-sharp edge.
2. The Spectrum of Grains: From Repair to Polishing
Here is a classification of the most commonly used grains, from the most aggressive to the gentlest:
2.1. "Renovation" Grains (200 to 400)
2.2. The "Working" Grains (600 to 1000)
2.3. "Finishing" Grains (3000 and Above)
3. The Crucial Importance of Sequential Order
You cannot go directly from a 4000 grit to a heavily damaged knife, nor can you go directly from a 400 grit to a 6000 grit. The sharpening process is a step-by-step process:
Step 1: Damage Removal (e.g., 400 grit)
You use 400 grit sandpaper to restore the geometry of your bevel. This grit leaves deep scratches, but it is fast.
Step 2: Scratch Removal (e.g., 1000 grit)
This is the most important step. The 1000 grit sandpaper shouldn't just sharpen; it should remove all the scratches left by the 400 grit. If you leave deep scratches, your edge will be brittle and the cutting edge won't last.
Step 3: Polishing and Finishing (e.g., 3000 grit)
The 3000 grit refines the scratches of the 1000 grit, making the wire smoother and more resistant to twisting.
The process is cumulative.
Sharpening is the process of replacing the scratches left by the previous grit with the finer scratches of the next grit. If you don't spend enough time on a grit, the previous scratches remain, and the cutting edge will be less durable.
4. The Advantages of Diamond Abrasives and Modern Systems
The choice of grain also applies to modern solutions:
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Diamond Abrasives: Often used in rolling systems or guided platforms, diamond discs or surfaces have a very high aggressiveness and are extremely fast at removing material. They are ideal for beginners as they require less effort and time.
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Simplicity: An effective modern sharpener often comes with the essential grits: a 400 grit (or diamond equivalent) for quick restoration and a 1000 grit (or ceramic/diamond equivalent) for finishing and polishing. This simplifies the learning curve by eliminating the need to buy 6 or 7 different stones.
5. 🗃️ Summary: The Role of Key Grains
✨ Conclusion and Next Step
You now have a firm grasp of the three theoretical pillars: the anatomy of the cut, the importance of the angle, and the role of the grit. Choosing the right abrasive is just as important as maintaining the angle.
The question now is: How to apply these grits and this angle? Should we choose a whetstone, a sharpening steel, or a more modern and safer method?
In our next article, we will review the main sharpening methods, comparing their advantages and disadvantages, and clarifying the time and safety constraints.
➡️ Go to Article 4: Stone, Sharpening Steel or Modern Sharpener: Comparison of Sharpening Methods.
